The ultimate objective of the proposed study is to increase the effectiveness of two manualized treatments for adolescent drug abuse by investigating the relation of treatment adherence and therapist competence to treatment outcomes. The study will examine existing data from a randomized clinical trial comparing multidimensional family therapy (MDFT) and individual cognitive-behavioral therapy (CBT), which represent two widely practiced, empirically supported treatment approaches for adolescent substance use. Treatment adherence and therapist competence have been identified as critical elements of manualized treatment implementation and as key predictors of therapeutic gains in both adolescent and adult populations. Studies that illuminate the associations among adherence, competence, and outcome are vital for developing more effective, targeted, and transportable therapy models for dissemination in diverse clinical settings. Subjects will include 143 inner-city, primarily African American, juvenile-justice involved adolescents and their caregivers. Adolescents and caregivers completed pre- and post-treatment measures of drug use and drug involvement, externalizing and internalizing symptoms, prosocial behavior, and family functioning. Archived videotapes of therapy sessions will be reviewed to assess treatment fidelity, therapist skill, and therapeutic alliance. Study hypotheses will test both the direct and indirect effects of adherence and competence on adolescent drug use and comorbid symptomatology. Structural equation modeling will examine whether: (1) for MDFT, greater adherence and competence produce better outcomes by means of improving parenting skills and family relationships; (2) for CBT, greater adherence and competence produce better outcomes by means of increasing adolescent self-efficacy and prosocial involvement; (3) for both treatments, the effects of treatment adherence are moderated by therapist competence and therapeutic alliance. This study will be among the first to explore the relation between treatment adherence and outcome, and the very first to study therapist competence, with an adolescent drug-using sample.